Xslt, Xml & Xhtml

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Ok so I am working on a project at work that involves XSLT. I struggling through it here as I have very little knowledge on it.

I would like to know of any good resources for learning this technology or any good books one can recommend. I hate books that talk on a very technical level. Rather ones that explain in simplistic terms, what it does, what I can achieve and where its best applied.

I know of a CMS called Symphony that uses this technology in its templating system, but I am unsure why its so powerful as opposed to normal CSS / XHTML?

My understanding so far is that if you have data in XML form you can transform it into XHTML through XSLT. I think it also seperates some of the programming logic from the display layer.

Any clarification would be appreciated.